This invention relates generally to discharge valves and, more particularly, to a discharge valve adapted for use with pumps used on mobile fire fighting equipment to deliver water at high pressure to fire hose lines. The discharge valves to which this invention is directed are mounted on the fire truck to control the flow of water from the delivery end of a high pressure fire pump to a fire hose which is connected to a discharge nozzle at the downstream end of the discharge valve.
Since the discharge nozzle must extend beyond the panel of the fire truck and the pump delivery outlet is generally spaced a substantial distance from the panel, the discharge valve of the indicated type must be provided with some means for conveniently connecting the delivery end of the pump to the valve chamber of the discharge valve. Also, if the discharge nozzle of the valve extends in a horizontal direction, a fire hose connected thereto will tend to crimp as it hangs downwardly to the ground which could choke off the flow of water under some pressure conditions. On the other hand, when high pressure water is supplied to the hose, the hose tends to stand out horizontally a substantial distance to cause interference with the firemen working around the fire truck. Further, because of the high pressure of the liquid discharged from the fire pump, the hose connected to the outlet of the discharge valve could be damaged if the valve is held partially closed or "gated" unless it is protected from the resultant high velocity stream. Accordingly, it would be desirable to provide a discharge valve of the indicated type which overcomes the above-discussed problems involved in the delivery of high pressure water to a fire hose.
The discharge section of the fire pump equipment should also be provided with some means of handling the water which remains in the fire hose at the time the fireman shuts off the pumping system. Thus, if the fire hose is strung to a remote location and/or extends to a height of several stories, there is a substantial amount of water in the hose at the time the pump is shut off by the fireman. If the hose were simply disconnected from the discharge valve nozzle, the water within the hose would then run all over the area adjacent the fire truck which could be messy and provide an unsafe condition especially in freezing weather. Thus, the discharge valve should be provided with a drain valve which serves to permit the quick draining of the water from the fire hose in a manner such that it could be directed to intenal piping which is discharged underneath the fire truck at a safe location.